1. Field of the Invention
The present invention relates to oil field tools, and more specifically, to a deflector assembly.
2. Description of the Related Art
Historically, oil field wells are drilled as a vertical shaft to a subterranean producing zone forming a wellbore, the wellbore is lined with a steel tubular casing, and the casing is perforated to allow production fluid to flow into the casing and up to the surface of the well. In recent years, oil field technology has increasingly used sidetracking or directional drilling to further exploit the resources of productive regions. In sidetracking, an exit, such as a slot or window, is cut in a steel cased wellbore typically using a mill, where drilling is continued through the exit at angles to the vertical wellbore. In directional drilling, a wellbore is cut in strata at an angle to the vertical shaft typically using a drill bit. The mill and the drill bit are rotary cutting tools having cutting blades or surfaces typically disposed about the tool periphery and in some models on the tool end.
Generally, components including an anchor, a deflector coupled to the anchor and a rotary milling assembly that progresses downward along the deflector are used to cut the angled exit through the casing in the wellbore. The deflector is an elongated cylindrical wedge-shaped member having an inclined concave deflection surface and guides the angle of the rotary milling assembly progressively outward to cut the exit. One or more of the components are attached to a tubing member, such as drill pipe or coiled tubing, that is used to lower the components into the wellbore. The anchor typically is a bridge plug, packer or another supporting or sealing member. The anchor is set in a downhole position and extends across the wellbore to form an abutting surface for placement of subsequent equipment.
Sidetracking or forming a lateral wellbore generally requires three “trips”. The first trip sets the anchor in the wellbore, the second trip sets the deflector to the anchor and the third trip actuates the milling assembly to cut the exit along the deflector. Such operations are time consuming and expensive.
Therefore, a need exists for an improved method and apparatus of forming a lateral wellbore.